Assuming this deity exists you were referring to, it means the ability to regenerate limbs was given to some species. These species are lesser creations than the most important life creation that the deity made - humans. Why wasn't the ability to regenerate limbs given to humans?

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We have the best evolutionary advancement of any species. A considerably higher level of brain function

Well, if we have the "best evolutionary advancement of any species" why can't we regenerate limbs? Or do you want to take back that statement?